The invention provides a silicon carbide chemical mechanical polishing liquid with improved pH value stability, wherein the polishing liquid comprises an oxidizing agent, a high-hardness abrasive material and a pH value stabilizer, and the pH value stabilizer is aluminum nitrate. According to the present invention, the polishing liquid can well maintain the pH value stability during the chemical mechanical polishing, and has advantages of good dispersion stability and uniform dispersion; by adding the pH value stabilizer aluminum nitrate to the polishing liquid, the pH value stability of the polishing liquid during the chemical mechanical polishing is strong, and the polishing liquid is not easily subjected to hard agglomeration; and the polishing liquid is environmentally friendly, and can be used in a circulating material supply manner.